In the world of light airplane manufacturing, Cessna has figured out one thing better than any other single manufacturer: There’s a difference between people who talk about buying airplanes and people who actually buy them. The people who talk gave up the Cessna Skyhawk for dead when it was reintroduced in 1997; the people who buy made it the second best-selling single in 2006 behind the Cirrus SR22. It will occupy the same position when the 2007 sales figures are tallied. Not bad for an airframe conceived in 1956 and still selling against the cutting-edge best from Cirrus, Diamond and others. Incredibly, Cessna isn’t done with the Skyhawk yet, having announced a Thielert-powered diesel version last fall at AOPA Expo in Hartford and, as of press time, it has dropped the 160-HP R-model from the lineup. Given Cessnas confidence in the 172, we wondered how the four variants of the Skyhawk-two versions of the 180-HP gas model and two versions of the new diesel-stack up against each other and against an older Hawk. When Cessna returned to single-engine piston production in 1996 for the 1997 model year, the task wasnt as simple as Cessna or buyers may have assumed. The 50-year-old design had to be recertified under new standards, to meet modern buyer expectations, ergonomic, style and maintenance upgrades were required and the new versions would also need a new engine. Although it planned to reintroduce the 182 and 206 too, Cessna initially focused on the Skyhawk alone. At $135,000 retail, the price was about twice as much as the last new Skyhawk to emerge from Wichita, the 1986 172P. At Oshkosh in 1996, there was open skepticism that Cessna would be able to justify the price increase after a decade of absence from the market. What the skeptics didnt get-but Cessna did-was that there wasnt a comparable airplane out there, not from Piper, nor Diamond, nor Cirrus nor anyone else. If you wanted a new Cessna, this was it. Second, inflation and 10 years of litigation horror stories had ingrained in buyers minds that airplanes would never be cheap because of insurance costs, not just for the manufacturer, but for everyone else who had so much as a nut, bolt or wire on the airplane. And when it emerged, the 172 was, well, nice. It wasnt terrifically special, but was a cut above the 172P. It had a clean metal panel, great upholstery with crashworthy seats, better seatbelts, modern interior plastics and the fuel-injected 180-HP Lycoming IO-370-L2A de-rated to 160 HP was a strong selling point. 
Upscale Models
Compared to Cessnas 1978 piston heyday, the 172R didnt set the world afire sales wise, but it did we’ll enough. Whats axiomatic in cars is also true in airplanes: The basic model begets a higher-price, tarted-up version that yields more margin for the manufacturer and perceived greater value for the buyer-enter the Cessna 172S/Skyhawk SP.
Cessna had always had the full 180-HP model on a back burner, but who would buy a 160-HP airplane if they knew that the same engine would produce more horsepower in the same airframe? In essence, the reason for two models of the same airplane is pure marketing. When the initial excitement of the new 172 wore off, the model needed a nudge to keep the line moving. In 1998, the 172 SP appeared and is now Cessnas top-selling single in volume, if not dollars. (The Turbo Skylane is second, and the 172R and straight 182 tie for third.) The SP made full use of the Lycoming engine by allowing increased RPM from 2400 to 2700. Cessna accomplished this rather simply by using the McCauley 1A170E/JHA 7660 (76-inch length/60 pitch) rather than the R models 1C235/LFA7570 (75-inch/70 pitch) and adjusting the mags. Twenty more horses allowed Cessna to increase the gross weight to 2550 pound and change. (The model we flew had a ramp weight of 2557 pounds.) The R-model 172 has a gross-weight limit of 2450 pounds. The SPs advertised maximum useful load is 837 pounds versus 758 pounds for the R-model.
Other differences are few and minor. An autopilot is available in the SP, first the Bendix/King KAP140 and now the fully integrated Garmin GFC 700. The SP is (generally) distinguishable with its polished rather than painted spinner and most roll out the door with rearseat airbag shoulder harnesses, a $1625 option.
The base price for the 172R was recently raised from $219,500 to $234,500 and it will be available only through mid-2008 and only with the Garmin G1000. Going forward after that, only 180-HP gasoline models will be sold in two variants: The S-GA selling for $254,500 and the SP at $283,500.
With its 180-HP engine, the S is technically a different model than the R, but the two S models remaining in the line are essentially differentiated by options. The S is the old SP and is fully equipped with the GFC 700, XM-based datalink weather and leather seats. The S-GA is the stripped down model-G1000, but no autopilot and fabric seats. Both have air conditioning as a $28,100 option, along with TAWS, airbag seatbelts and other options.
Enter the Diesel
In the December 2007 issue of
Aviation Consumer, we offered a first look at the new Cessna 172 TD for turbocharged diesel. The version we flew and examined was a test article, so we have to reserve final judgment on the TD for a later date. Specs wise, Cessnas current numbers on the TD claim a maximum gross weight of 2552 pounds with a useful load of 744 pounds, which is comparable to the R-model 172, but about 93 pounds less than the S.Our report on Diamonds experience with diesels revealed that lack of engine